The present invention relates to a new and distinct cultivar of Japanese pear tree (Pyrus pyrifolia), and particularly to a russet type pear tree forming mid to late season ripening fruits having excellent quality, and having a significantly strong resistance to black spot disease.
In Japan, recent trends in distribution of russet type Japanese pear cultivars leans towards excellent cultivars, known as xe2x80x98Hosuixe2x80x99 (unpatented in the U.S.) and xe2x80x98Kosuixe2x80x99 (unpatented in the U.S.). However, a new excellent variety which can be harvested subsequent to xe2x80x98Hosuixe2x80x99 is required.
The present new variety of Japanese pear tree was a cross-seedling which originated from a crossing between xe2x80x98162-29xe2x80x99 (♀) (the seed parent) (unpatented in the U.S.) and xe2x80x98Kosuixe2x80x99 (♂) (the pollen parent). The seed parent xe2x80x98169-29xe2x80x99 is a russet type Japanese pear variety having large fruits with excellent quality, ripening slightly late in the season, and having resistance to black spot disease, and was bred by a crossing between xe2x80x98Niitakaxe2x80x99 (unpatented in the U.S.) and xe2x80x98Hosuixe2x80x99. The crossing between xe2x80x98169-29xe2x80x99 and xe2x80x98Kosuixe2x80x99 was carried out in 1985, seeds were obtained, and seedlings from the seeds were planted at a selection field in 1987. The tree bore fruit for the first time in 1990, and the maturation period, resistance to disease and the quality of the fruit satisfied the above-stated purpose. Thus the tree was selected as the first selection in 1991, and subjected to local adaptability tests from 1992 at 34 experimental stations in the main pear growing regions, such as Saitama-ken, Tottori-ken, Chiba-ken, Ibaraki-ken, of Japan, as the strain number xe2x80x98Pear Tsukuba No. 47xe2x80x99. As a result, this new variety was judged to be a russet type pear variety having good quality and harvestable between xe2x80x98Hosuixe2x80x99 and xe2x80x98Niitakaxe2x80x99, and this new variety of Japanese pear tree was named xe2x80x98Akizukixe2x80x99 in 1998. The genus and species of the variety is Pyrus pyrifolia. 
This new and distinct variety of Japanese pear tree xe2x80x98Akizukixe2x80x99 was asexually reproduced at the National Institute of Fruit Tree Science, Ministry of Agriculture, Forestry and Fisheries (MAFF), at 2-1, Fujimoto, Tsukuba-shi, Ibaraki-ken, Japan, by grafting and the homogeneity and stability thereof were confirmed.
The following description is based on observation of a 12 year old plant grown by trellis training, with fertilizer applications at a rate of N:P:K =10:10:10 Kg/10 a. The observed plant was the original plant raised from a seedling, as opposed to a plant grafted on a rootstock. This new variety has a strong vigor and light greenish-brown, thick shoots. Bearing of spurs of the variety is average and that of axillary flower buds is few to average, and both less than for xe2x80x98Kosuixe2x80x99, xe2x80x98Hosuixe2x80x99 and xe2x80x98Niitakaxe2x80x99. Flowering time of the variety is late, the same as xe2x80x98Kosuixe2x80x99, and both the color of the flowers just before opening and that of the opened petals are white. The number of petals of the variety are many, but fewer than for xe2x80x98Kosuixe2x80x99. The color of unopened anthers is deep yellowish pink, resembling that of xe2x80x98Kosuixe2x80x99. A fruit bearing tree was obtained after four years of culture in the Ibaraki-ken site. The new variety produces large sized, i.e., about 500 g, larger than xe2x80x98Hosuixe2x80x99 and smaller than xe2x80x98Niitakaxe2x80x99, oblate shaped fruits, having wide breath and medium depth of stalk cavity. Ripening of the variety is 10 days later than that of xe2x80x98Hosuixe2x80x99 and about 1 week earlier than xe2x80x98Niitakaxe2x80x99 in Ibaraki-ken, Japan. Self-compatibility of the variety is low, but neither early fruit dropping nor late fruit dropping are observed, and the fruit setting is good, and thus productivity of immature trees of the variety is considered to be much greater than that of xe2x80x98Hosuixe2x80x99. Occurrence of heart rot, water core and cracking of the fruits are not observed. The fruit of the new variety is russet type pear having yellowish red brown fruit skin with densely distributed medium sized dots. The ratio of calyx perpetual fruit of the variety is high. The flesh of the variety is white colored, soft, compact and the degree of browning of a cut end thereof is medium. The taste of the flesh is highly sweet, slightly sweeter than that of xe2x80x98Hosuixe2x80x99, and is weakly sour, between xe2x80x98Kosuixe2x80x99 and xe2x80x98Hosuixe2x80x99. Aroma of the fruit of the variety is less than, but the taste is as excellent, as compared to xe2x80x98Hosuixe2x80x99.
The new variety is distinguishable from xe2x80x98Kosuixe2x80x99 in having stronger vigor, thicker shoots, lighter color of the shoot; the color of scale leaf of flower bud is reddish brown, the color of flower just before opening is white. The new variety is also distinguishable in having large size fruit, the ratio of calyx perpetual fruit being higher and the harvest season being later. The new variety is distinguishable from xe2x80x98Hosuixe2x80x99 in having lighter colored anthers, later flower blooming term, and in having no water core and spheroidal shaped fruit.